The Supreme Court of California has accepted review of Montrose Chemical Corporation v. Superior Court, 14 Cal.App.5th 1306 (App. 2nd Dist. 2017), a decision in which the Court of Appeal required a policyholder to prove horizontal exhaustion to trigger excess insurance coverage. The Supreme Court’s decision to accept review comes in the wake of State of California v. The Continental Insurance Company, 15 Cal.App.5th 1017 (App. 4th Dist. 2017), in which the Court of Appeal rejected Montrose and applied a vertical exhaustion rule. Reversal of Montrose would provide a significant victory for policyholders seeking to maximize insurance coverage for long tail losses, and would correct significant analytical errors in the Montrose decision regarding the meaning of other insurance clauses.

On November 29, 2017, the Supreme Court of California agreed to review Montrose Chemical Corporation v. Superior Court, 14 Cal.App.5th 1306 (App. 2nd Dist. 2017), which applied horizontal exhaustion, rather than vertical exhaustion, to determine when excess insurance coverage could be triggered. SeeMontrose and Multiple Policy Periods. The Montrose decision conflicts with a subsequent decision of the Fourth District Court of Appeal, as well as the decisions of multiple other jurisdictions on this issue. By accepting the petition for review, the Supreme Court has the opportunity to resolve a split between the Second and Fourth District Courts of Appeal on this important issue and to reassert its jurisprudence regarding the application of “other insurance” clauses and “all sums” allocation.

In Montrose, the Court of Appeal held that where a loss triggers policies across multiple policy periods, a policyholder must demonstrate exhaustion of all triggered underlying policies before any excess policy will be called upon to pay a claim. Montrose Chemical argued that vertical exhaustion should apply in light of the California Supreme Court’s decision endorsing all sums allocation in State of California v. Continental Insurance Company, 55 Cal.4th 186 (Cal. 2012). In other words, Montrose Chemical sought a ruling that to trigger an excess policy, the policyholder need only demonstrate exhaustion of underlying coverage in the same policy period. The Court of Appeal rejected Montrose Chemical’s argument. The court held that the “other insurance” provisions in the policies required the policyholder to exhaust coverage horizontally, meaning that before any excess policy could be triggered, the policyholder would need to prove exhaustion of every triggered underlying policy without regard to the coverage term.

Less than two months after the Montrose decision was rendered, the Fourth District Court of Appeal rejected an insurer’s request to apply a horizontal exhaustion rule. SeeCalifornia v. Continental: Horizontal Exhaustion the Rule in California? Not So Fast. In State of California v. The Continental Insurance Company, 15 Cal.App.5th 1017 (App. 4th Dist. 2017), the Court of Appeal relied on California Supreme Court precedent to conclude that “other insurance clauses are intended to apply in contribution actions between insurers, not in coverage litigation between insurer and insured.” Id. at 1032 (citing Dart Indus. v. Commercial Union, 28 Cal. 4th 1059 (Cal. 2002)). Accordingly, the court held that vertical exhaustion applied, and the policyholder could access excess coverage as soon as the underlying limits for that particular coverage period were exhausted. The court rejected Montrose, noting that “to the extent that the court’s reasoning is irreconcilable with ours, we disagree with it.” Id. at 1036 n.5.

Until the Supreme Court of California resolves this dispute, the Court of Appeal’s decision in Continental and the Supreme Court’s decision to review Montrose provide strong ammunition for policyholders seeking to avoid horizontal exhaustion. Policyholders should also continue to closely scrutinize their policies to determine whether the policies include language limiting the scope of underlying insurance, and should consider whether the policies could be interpreted under the laws of a jurisdiction that more clearly provides for vertical exhaustion.